Hydraulically controlled punch press



Jan. 28, 1964 H. SCHMID 3,119,292

I HYDRAULICALLY CONTROLLED PUNCH PRESS Filed March a. 1960 2 Sheets-Sheet 2 Fig. 3

l N VEN TOR.

BY HEINRICH SCI-IMID ATTORNEY United States Patent Ofifice Patented Jan. 28, 1954 3,119,292 HYDRAULICALLY QQNTRQLLED PUNCH PRESS Heinrich Echmid, Rapperswil, Sanltt Gaiien, witzerland, assignor to Almatic A.G., Giants, Switzerland, a Swiss company Filed Mar. 3, 196%, Ser. No. 12,641 9 Claims. (Cl. 83-124) The present invention generally relates to a hydraulically controlled punch press and, more particularly, to a press of the aforementioned type wherein the punching tool comprises a punch member actuated by a ram and a press pad member displaceable relative thereto.

When producing stampings of high precision and quality of the cut surfaces, particularly in fine punching, it is necessary to hold the strip of material with a high degree of precision in the entire area adjacent the punch. This function is performed by the press pad member which is equipped with separate actuating or driving means in punch presses of the type considered. Despite complex and large shapes of the workpiece, the pressure exerted by the press pad member must be practically identical at all points of the working surface if the quality of the cut is not to be detrimentally affected.

With presses of this type heretofore known to the art, in which the driving means for the press pad member are arranged about the ram thus transmitting the pressure to the press pads only peripherally, unavoidable deflection problems arise which prevent a cutting precision beyond a certain degree from being obtained.

It is consequently an important object of the present invention to completely eliminate such deflection problems.

A further object of the present invention is the provision of means for uniform transmission and distribution of pressure from the driving means of a pressure pad member to a workpiece.

These and other objects of the present invention will become better apparent from the following description when taken in connection with the accompanying drawing in which embodiments of the punch press according to the present invention are shown in vertical section in the drawing, only the members necessary for the understanding of the invention being represented, and in which:

FIG. 1 shows a first embodiment of a press head with a central punch, a hydraulically operated ram and a press pad plunger also hydraulically controlled;

FIG. 2 shows a modification of the embodiment according to FIG. 1, a two-piece punch being provided, and

HQ. 3 shows an enlarged view of the tool of a further variant.

It will be seen that the present invention generally provides for the arrangement of the driving plunger for the press pad within the punch system. The driving plunger for the press pad preferably operates on the press pad via pressure transmitting members or bolts which extend through a bridge portion of the punch system being in direct operative connection with the punch. Consequently this arrangement enables the press pad to be actuated directly and linearly by its associated plunger while the deflection problems will arise in the punch system where they are entirely harmless.

It will further be seen that the embodiments disclosed relate to hydraulically controlled punch presses in which the press pad plunger is operated by means of a hydraulic pressure cushion in dependence on the speed of the punch or the ram, as disclosed and described in my copending application Ser. No. 731,711 of April 29, 1958, now Patent No. 3,084,580.

Referring now more particularly to the drawing, it will be seen that in FIG. 1 the reference numeral 1 designates the ram displaceably arranged in the press frame and hydraulically controlled via the lines 2 and 3. The numeral 4 designates the primary pressure chamber for the ram 1 and situated above the latter and connected with hydraulic line 2. The ram 1, which is formed by a substantially cylindrical member, operates directly on a horizontal bridge member 5 connected to the ram in a manner not shown and carrying the punch 6. The punch 6 cuts the stamping from the work or strip of material 8 which rests on the bottom die h and bears against a counter punch 10 which, in turn, is subjected to the pressure of a hydraulic medium 12 via a plunger 11. The hydraulic medium for the control of the hydraulic counterpressure preferably communicates with the hydraulic control system (not shown) via the line 13.

Within the ram 1 a further or secondary pressure chamber 14 is provided in which a press pad plunger 15 is arranged for upward and downward displacement. The plunger 15 operates directly on two or more pressure transmission bolts or members 16 which extend through the bridge member 5 and operate directly on a press pad member 17. Bolts 16 are slidably guided in bridge member 5 and abut with their end faces against press pad plunger 15 and press pad member 17, respectively.

The secondary pressure chamber 114 communicates, via a conduit 18, with a chamber 19 recessed in the cylindrical surface of the ram 1, chamber 19 in turn com- 'rnunicating with the hydraulic control system via a conduit line 29 in the machine frame and, by way of example, leading to an efiiux regulator of which the flow resistance reacts on the press pad plunger 15. The press pad pressure chamber 14 is, therefore, connected to the hydraulic control system via a passage open in all operating positions of theram.

While the pressure of the press pad plunger 15 operates linearly and directly on the press pad member 17 through the bolts 15, the punch pressure is transmitted to the punch 6 via the bridge 5 by the ram 1; transmission is thus effected in a broken line of force. Deflections may therefore occur in the bridge member 5, they will not, however, practically affect the perfect function of the control punch 6.

In the embodiment according to FIG. 1 the press pad member 1'7 covers the entire working surface of the workpiece 8 when the latter is being processed. With stamping strips of greater dimensions it may, however, occur that the press pad plunger member itself does not extend over the entire workpiece. In such cases, a pressure distributing plate may be employed from which the holddown pressure is linearly transmitted, again via pressure bolts, to particularly suitable points of the press pad. Such an example is represented in FIG. 2.

The ram 25 is again displaceably arranged in the press frame or housing and hydraulically controlled as in FIG. 1. Ram 25 acts directly on a bridge member 26 which, in turn, transmits the punch pressure to the two punches 2.7. The two punch sections 27 may also be combined to form a single punch, such as an annular punch. The reference numeral 28 here designates counter punches or portions thereof.

In the embodiment of FIG. 2 again, several pressure bolts 31 extend through the bridge member to operate on the various portions or areas of the press pad member 31 which clamps the work 32 at points particularly favourable for the punching process. Since these points are so widely spaced in this embodiment that linear pressure from the press pad plunger 33 is not possible owing to the fact that its diameter is too small, a pressure distributing plate 34 is inserted intermediate plunger 33 and bolts 30 which linearly transmits the hold-down pressure via the bolts 36 to the press pad member 31. As will be seen from FIG. 2, the pressure distributing plate 34 is anazsz 3 slidably arranged in a corresponding recess formed within the punch bridge 26.

Attached to the bridge 26 of the punch system is a retaining ring 35 which extends underneath the press pad member 31 to limit the stroke thereof within the punch system and to retain member 31 during the return movement of the punch.

The press pad plunger 33 is again controlled by a hydraulic pressure cushion in analogy with FIG. 1, the said cushion being indicated by the arrows P.

FIG. 3 shows the lower portion of the entire punching tool in cross-section and drawn to an enlarged scale. The ram 40 operates directly on a punch bridge 41 which in turn transmits the pressure to an annular punch 42 attached thereto by means of the screws 43. Enclosed in the ram 40 in a manner previously described is the press pad plunger 44 which acts linearly and axially, via pressure bolts 45, on the press pad member 46, which is also of annular form and provided, in a manner known in the art, with at least one cutting edge 47 at its lower side of which the inner chamber holds or forces the material against the punch during the punching process.

This tool is designed to punch a flat ring 48 from the punching strip 49, a circular disk 50 remaining at the center which in turn must be removed from the stamping 48. This is performed by a punch die arranged in the lower portion of the tool which is not shown. Associated with the punch die is an insert member or stripper pin 51 in the top of the tool which also extends through the punch bridge 41 and the hollow punch tool 42, and rests on the press pad plunger 44. The stroke of the insert member 51 relative to the punch 42 is substantially similar to that between the punch 42 and the press pad member 46. The insert member or stripper pin 51 operates as an ejector for the central portion of the punching strip when the punch is withdrawn.

Attached to the punch bridge 41 by means of screws 52 is a retaining ring 53 which extends underneath an annular shoulder 54 of the press pad 46. This retaining ring limits the stroke or displacement of the press pad on the one hand and carries the said pad upwardly when the punch system performs its upward movement.

The tool according to FIG. 3, which shows the holddown system in two extreme positions separated by the axis of symmetry SS, operates as follows:

At the beginning of the punching process, the entire tool moves downward and approaches the punching strip 49; the press pad plunger, insert member and pressure pad member being located in their lowermost position 44a, 51a and 46a, respectively, as represented on the right hand side of line SS. After engagement of the punching strip, the latter offers resistance first to the press pad member and the insert member. Further downward movement of the punch system under the pressure of the ram 40 on the one hand forces the punch 42 into the material and, on the other hand, builds up a hydraulic pressure on the press pad plunger 44. In accordance with the speed of the punch, the cutting edge 47 is forced into the punching strip (cf. trace 55) while the punch penetrates the punching strip and cuts out the stamping 48. During this operation, the punch die has forced out the disk 50 in the upward direction, on which only the insert member bears under the influence of the lesser pressure of the press pad member. In the final position of the punch system, the press pad member, insert member and press pad plunger are in their upper relative extreme positions 46b, 51b and 44b, respectively, as shown to the left of line S-S in FIG. 3. The return movement of the punch system is then initiated (as by the supply of the hydraulic medium through line 3 in FIG. 1), the hydraulic control again increasing the pressure on the press pad plunger while the hold-down system in the punch system is forced downward. The press pad member 46 serves as stripper for the punching strip 49 and the insert member 51 as ejector for the round disk 50 which is pushed out of the annular die 42. The retaining ring 53 pulls the press pad member 46 along while the tool returns to its initial position.

In the embodiment described in connection with FIG. 3, the press pad plunger 44 again operates linearly on the press pad member 46 via the pressure bolts 45, while the ram 40 actuates the punch 42 via the punch bridge member 41.

The arrangement described is naturally applicable to all types of hydraulically controlled punch presses and practically all punching shapes encountered. Moreover, it is possible to drive the ram mechanically in a manner known in the art, whereas the pressure on the plunger is controlled in the manner described above.

In order to ensure maximum fixation of the punching strip and, if necessary, the displacement of the material towards the punch, the bottom die (9 in FIG. 1) may also be provided with a cutting edge.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. A punch press for producing stamped articles, comprising a ram member internally provided with a cylindrical chamber, plunger means arranged in said cylindrical chamber for movement relative to said ram member, means for supplying a hydraulic medium under pressure to said cylindrical chamber to act upon said plunger means, punch tool means provided with a hole rigidly secured to a face side of said ram member and coaxially arranged with respect to said cylindrical chamber, pressure pad means surrounding said punch tool means and movable relative to said ram member, a plurality of pressure transmitting members extending between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means to said pressure pad means, stripper pin means extending from said cylindrical chamber into said hole of said punch tool means for removing punched out material therefrom, said plunger means defining a common drive for said stripper pin means and said pressure transmitting members.

2. A punch press for producing stamped articles, comprising a cylindrical ram member provided with a cylindrical chamber opening in a lower end face thereof, plunger means arranged in said chamber for movement relative to said ram member, means for supplying hydraulic medium under pressure to said cylindrical chamher to directly act upon said plunger means, bridge means supported by said lower end face of said ram member covering said cylindrical chamber, punch tool means provided with a hole rigidly secured to said bridge means and coaxially arranged with respect to said cylindrical chamber, pressure pad means surrounding said punch tool means movable relative to said ram member, said bridge means and said punch tool means, said pressure pad means being provided with a projecting peripheral rim circurnjacent said punch tool means adapted to bear against a workpiece during a punching operation to force waste material inwardly in the direction of said punch tool means, a plurality of pressure transmitting members between said plunger means and said pressure pad means and extending through said bridge means in slidably guided relation, said pressure transmitting members being arranged in even angularly spaced relation about said punch tool means for transmitting pressure acting upon said plunger means to said pressure pad means and uniformly distributing said pressure thereon, stripper pin means extending from said cylindrical chamber into said hole of said punch tool means for ejecting punched out material therefrom, said plunger means serving as a common drive for said stripper pin means and said pressure transmitting members.

3. A punch press for producing stamped articles from a metallic workpiece, comprising a unitary ram member internally provided with a cylindrical chamber opening in a lower end face thereof, plunger means arranged in said chamber for movement relative to said r-am member, means for supplying hydraulic medium under pressure to said cylindrical chamber to act upon said plunger means, bridge means connected to said lower end face of said ram member and covering said cylindrical chamber, hollow punch tool means rigidly secured to said bridge means and coaxially arranged with respect to said cylindrical chamber of said ram member, pressure pad means surrounding said punch tool means and movable relative to said ram member, said pressure pad means being provided with a projecting peripheral rim lcircumjacent said punch tool means adapted to bear against a workpiece during a punching operation to force waste material inwardly in the direction of said punch tool means, said bridge means and said punch tool means, a plurality of bolt members disposed between said plunger means and said pressure pad means and extending through said bridge means in slidably guided relation, said bolt members being arranged in even angularly spaced relation about said punch tool means for transmitting pressure acting upon said plunger means to said pressure pad means and uniformly distributing said pressure thereon, stripper pin means extending from said cylindrical chamber through said hollow punch tool means for ejecting punched out material therefrom, said plunger means defining a common drive for said stripper pin means and said bolt members.

4. In a punch press for producing stamped articles; the improvement comprising a frame, a unitary ram member reciprocably mounted in said frame for actuation of at least one face of said nam member by a pressure medium, said ram member being internally provided with a pressure chamber, plunger means located in said pressure chamber, means for directing a fluid medium into said pressure chamber for [direct contact with said plunger means for displacing said plunger means, hollow tool means supported by the other face of said ram member, pressure pad means encompassing said tool means and movable relative to said ram member, pressure transmitting means interposed between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means, stripper pin means extending from beneath said plunger means into said hollow tool means for ejecting punched out material therefrom, said plunger means acting as a common drive for said stripper pin means and said pressure tnansmitting means.

5. In a punch press for producing stamped articles; the improvement comprising a frame, a unitary ram member reciprocably mounted in said frame for actuation of at least one face of said ram member by a pressure medium, said ram member being internally provided with a pre sure chamber, plunger means located in said pressure chamber, means for directing a fluid medium into said pressure chamber for direct contact with said plunger means for displacing said plunger means, bridge means carried by the other face of said ram member, hollow tool means supported by said bridge means, pressure pad means encompassing said ltOUl. means and movable relative to said ram member, pressure tnansmitting means interposed between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means, stripper pin means extending from beneath said plunger means into said hollow tool means for ejecting punched out material therefrom, said plunger means acting as a \common drive for said stripper pin means and said pressure transmitting means.

6. A punch press according to claim 5, wherein a retaining ring is attached to said bridge means, said retaining ring extending underneath said pressure pad means for the purpose of limiting the stroke thereof and of holding it during the return movement of the tool means.

7. In a punch press for producing stamped articles; the improvement comprising a frame, a unitary ram memher reciprooably mounted in said frame for actuation of at least one face of said ram member by a pressure medium, said ram member being internally provided with a pressure chamber, plunger means located in said pressure chamber, means for directing a fluid medium into said pressure chamber for direct contact with said plunger means for displacing said plunger means, bridge means supported by the other face of said ram member, hollow tool means carried by said bridge means, pressure pad means encompassing said tool means and movable relative to said ram member, pressure transmitting means interposed between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means, stripper pin means extending from beneath said plunger means into said hollow tool means for ejecting punched out material therefrom, said plunger means acting as a common drive for said stripper pin means and said pressure transmitting means.

8. In a punch press for producing stamped articles, the improvement of: a frame provided with a compartment, a ram member slidably arranged in said compartment and defining above at least one face of said ram member a primary pressure chamber for receiving a primary pressure medium for displacing said ram member, means for feeding said primary pressure medium into said primary pressure chamber, said ram member being internally provided 'with a secondary pressure chamber, plunger means displaceably arranged in said secondary pressure chamber, means for directing a secondary pressure medium into said secondary pressure chamber for direct contact with said plunger means for displacement of the latter, said ram member being provided with passage means communicating said secondary pressure chamber with said compartment of said frame in all operating positions of said ram member, hollow tool means supported by the other face of said ram member, pressure pad means surrounding said tool means and movable relative to said ram member, pressure transmitting means interposed between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means, stripper pin means extending from beneath said plunger means into said hollow tool means for ejecting punched out material therefrom, said plunger means acting as a common drive for said stripper pin means and said pressure transmitting means.

9. In a punch press for producing stamped articles, the improvement of: a frame provided with a compartment, a ram member slidably arranged in said compartment and defining above at least one face of said ram member a primary pressure chamber for receiving a primary pressure medium for displacing said ram member, means {for feeding said primary pressure medium into said primary pressure chamber, said ram member being internally provided with a secondary pressure chamber, plunger means displaceably arranged in said secondary pressure chamber, means for directing a secondary pressure medium into said secondary pressure chamber for direct contact with said plunger means for displacement of the latter, said nam member being provided with passage means communicating said secondary pressure chamber with said compartment of said frame in all operating positions of said ram member, said secondary pressure medium being fed into said secondary pressure chamber independently of said primary pressure medium but controllable as a function of the speed of said ram member, hollow tool means supported by the other face of said ram member, pressure pad means surrounding said tool means and movable relative to said ram member, pressure transmitting means interposed between said plunger means and said pressure pad means for transmitting pressure acting upon said plunger means, stripper pin means extending from beneath said plunger means into said hollow tool means for ejecting punched out material therefrom, said plunger means acting as a com '2? 8 mon drive for said stripper pin means and said pressure 2,534,292 Mueller Dec. 19, 1950 transmitting means. 2,704,125 Taylor Mar. 15, 1955 2,970,503 Chevallier Feb. 7, 1961 References Cited In the file of this patent 2,986,057 Novak May 30, 1961 UNITED STATES PATENTS 5 FOREIGN PATENTS 1,428,174 Luther Sept. 5, 1922 358,156 Great Britain Oct. 8, 1931 

1. A PUNCH PRESS FOR PRODUCING STAMPED ARTICLES, COMPRISING A RAM MEMBER INTERNALLY PROVIDED WITH A CYLINDRICAL CHAMBER, PLUNGER MEANS ARRANGED IN SAID CYLINDRICAL CHAMBER FOR MOVEMENT RELATIVE TO SAID RAM MEMBER, MEANS FOR SUPPLYING A HYDRAULIC MEDIUM UNDER PRESSURE TO SAID CYLINDRICAL CHAMBER TO ACT UPON SAID PLUNGER MEANS, PUNCH TOOL MEANS PROVIDED WITH A HOLE RIGIDLY SECURED TO A FACE SIDE OF SAID RAM MEMBER AND COAXIALLY ARRANGED WITH RESPECT TO SAID CYLINDRICAL CHAMBER, PRESSURE PAD MEANS SURROUNDING SAID PUNCH TOOL MEANS AND MOVABLE RELATIVE TO SAID RAM MEMBER, A PLURALITY OF PRESSURE TRANSMITTING MEMBERS EXTENDING BETWEEN SAID PLUNGER MEANS AND SAID PRESSURE PAD MEANS FOR TRANSMITTING PRESSURE ACTING UPON SAID PLUNGER MEANS TO SAID PRESSURE PAD MEANS, STRIPPER PIN MEANS EXTENDING FROM SAID CYLINDRICAL CHAMBER INTO SAID HOLE OF SAID PUNCH TOOL MEANS FOR REMOVING PUNCHED OUT MATERIAL THEREFROM, SAID PLUNGER MEANS DEFINING A COMMON DRIVE FOR SAID STRIPPER PIN MEANS AND SAID PRESSURE TRANSMITTING MEMBERS. 